Hi Polly,

I'm wondering why the soil is eroding. Is this something you should contact the city about and make sure everything was installed correctly?

Is the mulch behind the fence city property? It looks to me like someone has sprayed herbicide along the fenceline. Do you know if your friend did that or the city? Or is the dead grass because of erosion? 

I don't think you need to build up the soil. However, before I planted anything, I would want to know if someone is spraying herbicide. If I determined that no one is spraying herbicide, I would not plant daylilies. They do not have deep roots to hold the soil in place. Instead, I would choose a shrub or a few shrubs grouped together, because they have branching and deep roots to hold the soil and slow down the infiltration of water. If I didn't want a shrub, I would choose a native perennial grass and/or flowers.  If the areas gets full sun, you could easily make a native plant bed with Black-eyed susans (Rudbeckia hirta), little bluestem grass (Schizachyrium scoparium), native sunflowers (multiple species in the genus Helianthus), wild bergamot (Monarda fistulosa), and swamp milkweed (Asclepias incarnata). Once these plants are installed, you would have to water them until they got established, but after that they are pretty much care free. You would have to weed the bed, but you should not have to water or fertilize. 

Lindsey K. Kerr, MS, MHP (she, her, hers)
Consumer Horticulture Educator
Michigan State University Extension